Aircraft noise reduction apparatus

ABSTRACT

An aircraft, aircraft landing gear and apparatus including at least one attachment ( 15,17,76,93,94,111 ) for noise reduction purposes are provided. Such attachments are shaped and positioned on the landing gear to deflect air away from noise-inducing components ( 64,65 ) of the landing gear and to permit deflection and articulation movement and also stowage of the landing gear whilst the attachments are installed thereon. The attachments are not designed to be drag-reducing.

[0001] This invention relates to aircraft noise reduction apparatus, inparticular to apparatus to reduce noise emanating from landing gear ofthe aircraft when deployed on approach to landing.

[0002] The invention has particular application to commercial aircraftwhen landing at airports in or near to built up areas where aircraftapproach noise is an increasing nuisance with increasing frequency ofuse of airports and ever larger aircraft. Noise emanating fromcommercial aircraft, whether cargo aircraft and/or passenger carryingaircraft, is now an important environmental issue. The increasingfrequency of use of airports has led to aircraft of increasing sizebeing used. This in turn has led to greater noise being generated byeach aircraft in its approaches to the airport. Modern high bypass ratioturbofan engines are now extremely quiet on approach to landing anddominant noise on some aircraft types, perceived at ground level, isstarting to become the noise generated by landing gear and by high liftdevices on the wings.

[0003] This invention addresses the problem of aircraft noise, asperceived at ground level, generated by landing gear. Although noise islikely to be induced by any element which creates turbulence in theairflow past the landing gear, those elements which have been foundparticularly likely to create high noise levels are as follows:—elementswhich act as Helmholz resonators such as hollow axles, apertures,fastener fittings, spindles, etc; also elements likely to create smallvortices such as small protuberances, sharp edges; dresssings such assmall pipes, tubes, cables, and coil springs, etc. All such features areto be found aplenty on modern landing gear and tend to be more prevalentin the region of steering gear and wheel axles.

[0004] Although wind tunnel tests have been carried out on landing gearfully enclosed by fairings to determine noise levels in the far field,such full enclosure fairings are normally completely impractical foreveryday use on an aircraft. This is because articulation of the landinggear during deployment and retraction movement is prevented by thefairings and because very limited stowage space in the landing gear bayin most aircraft will not accommodate full enclosures owing to the spacewhich they take up. Additionally, full enclosure fairings render dailyvisual inspection regimes and maintenance of the landing gear almostimpossible. Firstly, this is because visible inspection through suchfairings is generally impossible and secondly because regular removal ofsuch fairings for inspection or maintenance is far too time consumingand difficult. To date therefore no practical solution to the problem oflanding gear induced airframe noise has been found.

[0005] According to a first aspect of the invention there is providedaircraft noise reduction apparatus including at least one noise-reducingattachment for landing gear of the aircraft shaped for positioning onthe landing gear to deflect air away from noise inducing components ofthe landing gear and to permit deflection, articulation movement andstowage of the landing gear with the attachment installed.

[0006] The attachments may comprise deflector screens adapted not tocompletely surround noise inducing components on the landing gear. Thesaid lack of a complete surrounding being for the purposes of allowingthe said access and foldability of the landing gear.

[0007] Induced noise is proportional to the sixth power of the relativevelocity of the airflow and component around which the air flows, andattachments of the invention are positionable to deflect incident airaway from noise inducing components, preferably into the free stream.

[0008] The attachments must withstand all aerodynamic loads and foreignobject damage, and it will be appreciated that the use of attachmentsaccording to the invention may increase landing gear drag.

[0009] Preferably a said attachment is shaped such that when positionedon the landing gear, airflow over the attachment during flight leavesthe attachment substantially in the free stream direction.

[0010] Preferably a said attachment is shaped to avoid or minimise anair stagnation region forming in front thereof when positioned on thelanding gear and in use. Such stagnation regions tend to increase bothdrag and noise emanating downstream of the stagnation region. The term“in front of” as used herein refers to a position upstream in theairflow, during flight.

[0011] In regions of the landing gear where incident air is acceleratedbetween components of the landing gear, such as struts, stays andactuators, at least one said attachment is preferably positioned todeflect incident air away from the said air-accelerating region. In thisway any noise-inducing components of the landing gear positioned in thesaid air-accelerating region will not be subject to the passage of suchaccelerated high speed air past them.

[0012] The apparatus may include an axle attachment positionable infront of an axle for nose gear of the aircraft to deflect air away fromnoise inducing components such as landing gear dressings in the regionof the axle.

[0013] The axle attachment may be shaped to shield items such as atowbar fitting on the nose gear and the said shaped portion is desirablyseparately removable or pivotable out of the way in order to provideaccess to such a towbar fitting without disturbing the remainder of theaxle attachment. Cam fasteners or other quick release fittings aresuitable for fastening the shaped portion.

[0014] The axle attachment may extend laterally into close proximitywith the wheels and may include generally cylindrical wheel extensionsextending between a central portion thereof and each wheel whereby todeflect air away from noise inducing components on the axle and at thesame time to deflect air away from a cavity formed within each wheel.

[0015] The wheel extensions preferably extend into close proximity witha rim of each wheel. Alternatively the wheels may be fitted with innerhub caps or wheel fillers. Such fillers may be of say foam materialformed in two opposing sections with wedge-shaped elements driven intoposition therebetween. The foam or like material is preferably coveredon the outside with a weatherproof material.

[0016] The axle attachment may include upper extension portions forpositioning on either side of a main leg of the nose gear to deflect airaway from torque link attachments usually sited on the axle.

[0017] The apparatus may include a said attachment positionable in frontof a steering mechanism for the landing gear. Such a steering mechanismhas been found to be prone to noise inducement including, as it usuallydoes, many sharp edges, apertures and sundry pipe and cable work.

[0018] Similarly, the axle attachment deflects air away from anotherregion of the landing gear particularly prone to noise inducement, i.e.the joint between the main leg and the axle, again liable to includesundry sharp edged fittings and pipe and cable work.

[0019] For circular landing gear components such as main legs oractuators positioned immediately in front of noise inducing components,transition strips of tape may be attached to the circular component oneither side thereof to encourage clean detachment of airflow therefromand to encourage airflow away from a region immediately behind thecircular component.

[0020] Where articulation and stowage permits it, components such ascircular legs or actuators may be fitted with trailing extensions fromeither side thereof. Such extensions, in combination with the component,may then act as an attachment according to the invention to deflect airaway from noise inducing components behind the said component withtrailing extensions.

[0021] The said apparatus may include at least one said attachmentpositionable in front of an apertured landing gear strut or stay todeflect air away from edges of the aperture.

[0022] For a said strut or stay having surfaces extending approximatelystreamwise in the airflow a said attachment may be shaped to blend inairflow leaving the attachment with airflow passing over the saidstreamwise extending surfaces. Alternatively, where further noiseinducing elements are positioned on the landing gear to the rear of thesaid attachment, the attachment may be flared or otherwise shaped alsoto deflect air away from the said rearward noise inducing elements. Inthis regard it has been determined that for an attachment to accelerateincident air is not unacceptable so long as the accelerated air does notpass over noise-inducing components.

[0023] A said attachment whilst being shaped to avoid any regions of airstagnation where possible may also be shaped or flattened as appropriateto avoid other elements of the landing gear or further attachments,during movement such as articulation and/or stowage of the landing gear.

[0024] Where the landing gear includes a wheeled bogie having a bogiebeam the apparatus may include an attachment in the form of an undertrayextending in front of and underneath the bogie beam to deflect air awayfrom noise inducing elements in the region of the bogie beam, forexample brake rods, bearings and their mountings, other fittings andsundry pipe and cable work.

[0025] An advantage of the undertray not extending above and behind thebogie beam is that inspection and maintenance access and air cooling arenot thereby prevented by the attachment.

[0026] Where the bogie beam is tilted upwardly at the front, duringapproach, the area of the bogie beam left exposed is downstream of theundertray and thus the passage of high speed air past noise inducingcomponents associated with the bogie beam is prevented by the undertrayattachment.

[0027] Preferably the undertray includes at least one door therein toprovide access to concealed items such as jacking points for the bogie.

[0028] The undertray may have a single curvature aerodynamic surface andmay be of a width to permit air to pass between the undertray and wheelson the bogie to cool brakes. Preferably the undertray includes a forwardupwardly extending aerodynamic surface blended smoothly into an undersurface extending underneath and along the bogie beam, desirably with afurther surface extending longitudinally of the bogie beam on eitherside of the undertray depending from lateral edges of the undertray,preferably orthogonal to the said aerodynamic surface. In this way airspilling over each lateral edge of the undertray in the region of wheelbrakes will be able freely to flow past the brakes but will not beaccelerated past the brakes by any funnelling effect of the surfacecontours of the undertray.

[0029] Where the bogie includes a pair of forward articulation links asaid attachment may comprise a pair of articulating fairings, onemounted to each articulation link with an aerodynamically contouredinterface being defined between the fairings. Preferably the saidinterface comprises a generally spherical element on one fairingco-operating with generally circular section tubing of the other. Thespherical element desirably has its centre coincident with a pivot axisbetween the articulating links.

[0030] Where the landing gear includes a door attached thereto extendingin a generally streamwise direction to one side of a main leg of thelanding gear a said attachment may comprise a deflector fairingextending from the door in front of at least the main leg of the landinggear. Preferably the fairing is positionable in sealing engagement withthe door and may additionally extend in front of any further struts,stays and/or actuators for the landing gear located in the vicinity ofthe main leg thereby to deflect air away from all said landing gearcomponents. For a main landing gear having a drag stay extendingupwardly in the vicinity of the main leg and a retraction actuatorsimilarly extending upwardly in the vicinity of the main leg, the saidfairing not only achieves deflection of the air away from any noiseinducing fittings on the main leg, but also deflects air away frompassages formed between any combination of the main leg, the actuator,the drag stay and the main leg door where air would otherwise beaccelerated therethrough usually past sundry noise inducing fittings.

[0031] For a large aircraft the undertray may be in excess of 2 metresin length and is desirably constructed to possess adequate longitudinaland torsional stiffness to enable handling when off the aircraft.

[0032] The front portion of the undertray desirably has extensionportions to extend around the lower articulation link fairing and thusprovide a smooth airflow in this area, upon approach to landing.Generally a main landing gear with a bogie will approach landing withthe rear wheels deflected downwardly and the front wheels deflectedupwardly. The undertray and lower articulation link fairing thusdesirably lie closely adjacent one another when the bogie is in approachconfiguration.

[0033] The undertray may be attachable to axles on the bogie, and/or tothe bogie beam itself by means of band-type clamps adapted to passaround the axle/bogie beam and through at least one part-annular chamberformed in an extension piece fixed to the undertray.

[0034] In general, all attachments will be as easily removable aspossible, employing either existing screw-type fasteners on the gearand/or clamps around items of the gear such as struts, stays and axles.Some attachments will inevitably need to be removed for maintenance, atsome stage, and here ease of removal and re-fitting is essential. Allattachments are also preferably retro-fittable to existing designs oflanding gear.

[0035] According to a second aspect of the invention there is providedaircraft landing gear including apparatus according to the first aspectof the invention.

[0036] According to a third aspect of the invention there is provided anaircraft incorporating landing gear fitted with noise-reductionapparatus according to the first aspect of the invention.

[0037] The invention will now be described by way of example withreference to the accompanying drawings of which:—

[0038]FIG. 1 is an orthogonal view of nose landing gear fitted withapparatus according to the invention,

[0039]FIG. 2 is an orthogonal cut away view of main landing gear whenfitted with apparatus according to the invention,

[0040]FIG. 3 is an orthogonal view of part of a nose landing gear fittedwith an attachment according to the invention,

[0041]FIG. 4 is a top plan view of a torque link with fairingattachment,

[0042]FIG. 5 is a section along the line V-V of FIG. 4,

[0043]FIG. 6 is a section through a nose landing gear lower drag staywith fairing attachment,

[0044]FIG. 7 is a side view of a landing gear articulation link withfairing,

[0045]FIG. 8 is a side detail view of a front end of an undertrayattachment according to the invention,

[0046]FIG. 9 is a section taken along the line IX-IX of FIG. 8, and

[0047]FIG. 10 is an orthogonal view of an aircraft main landing gearwith wheels removed to show landing gear dressings.

[0048] Referring to FIGS. 1 and 3, an aircraft nose landing gear isshown having wheels 1, 2, an axle 3 (see FIG. 3), a main telescopic leg4, and steering mechanism shown generally at 5, an upper drag stay 6pivotally connected to a lower drag stay 7 at pivot 8 and to the leg 4at pivot 9, pintle bearings 10, 11, a drag stay release mechanism 12 andtorque links 13, 14. The nose gear is fitted with various noise-reducingattachments as follows. All have been designed to provide the moststreamlined shape commensurate with maximum total noise reduction andproviding room for articulation of the landing gear during use, duringretraction/deployment and during stowage. Drag may actually be increasedowing to the fitting of the attachments. Shown in FIGS. 1 and 3 is anaxle fairing attachment 15; a lower torque link attachment 16 (shown inFIG. 1 only); a steering mechanism attachment 17; steering actuatorcovers 18, 19; a lower drag stay attachment 20 and main fittingattachments 21, 22.

[0049] Referring to FIG. 3, the axle fairing attachment 15 is clampedaround the leg 4 by a clamp (not shown). A lower hinged portion 23covers a towbar fitting 24 and may be hinged about the axis 25 foraccess to the towbar fitting. An upper portion 26 of the axle attachment15 has extension portions 27, 28 positioned to deflect incident air awayfrom lower pivots 29 of the lower articulation link 14. Cylindricalextensions 30, 31 extend between a central portion 32 of the attachmentand wheels 33. The cylindrical extensions 30, 31 extend in closeproximity with rims 117 of the wheels to prevent noise being generatedby the passage of incident air across Helmholz resonators formed by thewheels.

[0050] External wheel cover attachments 34 extend into close proximitywith rims 35 of each wheel whilst not overlapping the tyre 36, so thatinspection of the tyres is not interfered with. Such wheel covers may beannular in shape to fit around central forced-air-cooling ducts for thewheels and may be mounted thereon.

[0051] In FIG. 1 the lower torque link attachment 16 is generally domedbut with a scallop to provide clearance when the links 13 and 14 movetogether during compression of the main leg 4. Referring to FIGS. 4 and5 such an attachment as that shown at 16 is shown bolted into positionusing bolts 37, 38 passing through the attachment 16 for fasteningbehind a backing plate 39 placed behind an aperture 40 in the torquelink 14. Edges 41, 42 defining the aperture 40 are therefore covered bythe attachment 16, just as are edges 43, 44. It will be noted thatstreamwise extending surfaces 45, 46 are blended in with the attachment16 such that air leaving the attachment at positions 43, 44 blends withfree stream air passing over surfaces 45, 46.

[0052] The steering mechanism attachment 17 is a generally domed shapeformed to minimise any stagnation areas centrally thereof. Edge region47 is shaped and positioned to merge air leaving the attachment withfree stream air, tangential thereto. The region of the landing gearbehind the attachment 17 is prone to noise generation and thisattachment is effective for reducing noise emanating from the landinggear.

[0053] Steering actuator covers 18, 19 have domed ends 48, 49 andsmoothly curving portions 50, 51 covering actuator tubes (not shown) andsundry pipework (not shown).

[0054] Referring to FIGS. 1 and 6, the lower drag stay 7 has a fairingattachment 20 positioned in front thereof. The attachment 20 is notdesigned to fit closely with the drag stay 7 but is made deliberatelywider to deflect air not only past edges 52, 53 but also away from coilsprings 54, 55 of the drag stay release mechanism 12. It will be notedthat edge regions 56, 57 of the attachment 20 are shaped to blend in airleaving the attachment with free stream air. The coil springs 54, 55 maybe fitted with socks, preferably transparent for inspection purposes, toreduce induced noise.

[0055] Lastly, main fitting attachments 21, 22 cover apertures definedbetween the main leg 4, diagonal bracing member 58 and a pintle member59. The main fitting attachments are relatively planar on their frontsurface to allow space for articulation of the nose gear duringretraction and stowage.

[0056] It will be seen that the fitting of relatively brief fairingattachments to the nose gear has had the effect of covering many quitetroublesome areas of noise generation but that these attachments may beeasily removed for access and are in all cases designed to allow forcompression of the main leg and articulating movement of the nose gearand stowage thereof in its stowage bay (not shown). It will be notedthat in all cases the attachments are designed to be retro-fittable toan existing landing gear, clamping having been used throughout as amethod of attachment. Additionally, the relatively small size of theattachments~has kept additional weight to a minimum.

[0057] The skilled reader will note that the upper drag stay 6 has nofairing attachment thereon. This part of the drag stay is largelycontained within the fuselage of the aircraft.

[0058] Upper torque link 13 has not been fitted with a fairingattachment as it lies at least partly behind the steering mechanismattachment 17. Clearly an attachment could be fitted to this part of thelinkage if the particular landing gear design would substantiallybenefit from it.

[0059] Referring to FIG. 10, an aircraft main landing gear is shownminus wheels but with its dressings 60, 61, 62, 63 shown. The landinggear comprises a main telescopic leg 64, a retraction actuator 65, adrag stay 66, upper and lower articulation links 67, 68, upper and lowertorque links 69, 70, a bogie beam 71, axles 72, 73 and brake rods 74,75.

[0060] Dressings 62 are largely out of the airflow and do notsignificantly affect noise levels from the landing gear. Dressings 60,61, 63 are in the airflow when the landing gear is deployed on approachand are sources of noise from the landing gear, especially when combinedwith other components. It is believed that vortices shed from dressingsimpact on to other components then to generate noise.

[0061] Referring now to FIGS. 2, 7, 8 and 9, a main landing gear similarto the one shown in FIG. 10 is shown with various noise-reducing fairingattachments fitted, together with details of certain attachments.Referring to FIG. 2, parts common to FIG. 10 have been shown withidentical reference numerals. An undertray attachment 76 is shownclamped to the bogie beam 71 by clamps 77, 78 and also by clamps 79, 80(see FIGS. 8, 9) to the axles 72, 73. The undertray 76 has a singlecurvature aerodynamic surface 81 extending over a forward upwardlyextending portion 82 and a lower portion 83 extending under the bogiebeam. A rear curved portion 84 keeps incident air away from the rearaxle 73 and its dressings 61 (see FIG. 10). The undertray has a pair ofopenable access doors 85, 86 for access to jacking points (not shown).Depending from lateral edges 87, 88 of the undertray are a pair oflaterally facing surfaces 89, 90 extending longitudinally of the bogiebeam on either side of the undertray. The forwardly upwardly extendingportion 82 has extensions 91, 92 wrapping around a lower articulationlink fairing attachment 93 which works in conjunction with an upperarticulation link fairing attachment 94. With the landing gear in theapproach position as shown in FIG. 2 it can be seen that the forwardportion 82 of the undertray wraps neatly around the lower articulationlink fairing attachment 93 to provide a smooth aerodynamic contour oflow noise configuration. It will be appreciated that the forward portion82 of the undertray effectively deflects incident air away from thedressings 60.

[0062] The undertray is of a width to permit air to pass between wheels95, 96 and the undertray for brake cooling. The form of the edges 87, 88and longitudinally extending surfaces 89, 90 permits air to pass overbrake callipers (not shown) between the undertray and the wheels butdoes not funnel air through these regions at increased speed andtherefore create unnecessary noise. The shape of the undertray isgenerally adapted to deflect air away from noise inducing components onthe bogie beam and landing gear generally whilst affording maximumaccess to the upper and side parts of the bogie beam for inspection andmaintenance purposes. Weight saving is also achieved by thisconfiguration, relative to a full enclosure.

[0063] The clamps 79, 80 for clamping the undertray to the axles 72, 73comprise bands 97, 98 passing through part annular elements 99, 100attached to the undertray (see FIGS. 8 and 9). This method of fitting isextremely rigid, robust and of relatively light weight.

[0064] The articulation link fairing 93, 94 is shown in FIG. 2 and alsoin more detail in FIG. 7. It will be appreciated that the articulationlinks 67, 68 (see FIG. 10) work in conjunction with telescopiccompression of the main leg 64. For this reason the fairing attachments93, 94 must be able to pivot with respect to each other. Each isseparately clamped to its articulation link by clamps 101, 102, 103, 104(see FIG. 7) but the two interact with each other in region 105 aboutthe pivot centre. It will be seen that upper attachment 94 has a partspherical portion 106 adapted to pass inside a co-operating partcylindrical portion 107 of the lower attachment 93 during pivotingmovement of the articulation links. The centre of portions 106 and 107coincides with the pivot centre of the articulation links. A clearanceof 2 mm is preferred between portions 106, 107. Edge regions 108, 109 ofthe attachment are designed to deflect air leaving the attachments 93,94 away from noise-inducing elements on the main leg 64.

[0065] Referring to FIG. 2, forward drag stay 110, retraction actuator65 and main leg 64 are all shielded from the airstream by a doordeflector attachment 111 attached in sealing engagement to a wing skindoor 112 attached to the main leg 64. Owing to the way the landing gearis stowed in the bay, space is extremely tight in this area and thedeflector attachment 111 achieves the object of deflecting air away fromthe main leg, the actuator and the forward drag stay without interferingwith the stowage of the gear. Air which would otherwise have beenaccelerated between any combination of the leg, the retraction actuator,the forward drag stay and the door is therefore deflected away from suchpotential noise-inducing “channels” and around the main leg 64 into thefree stream. The attachment 111 is clamped by through bolts to theforward drag stay 110 and comprises a first portion 113 having agenerally concave aerodynamic surface 114 and a second portion 115having a generally convex aerodynamic surface 116.

[0066] Once again it will be seen that with relatively minimal use ofretro-fittable and easily removable attachments according to theinvention that all major noise-inducing areas of the landing gear havebeen protected from the airflow. At the same time articulation andstowage of the landing gear has not been hindered and additional weighthas been kept to a minimum.

1. Aircraft noise reduction apparatus including at least onenoise-reducing attachment (15,17,76,93,94,111) for landing gear of theaircraft shaped for positioning on the landing gear to deflect air awayfrom noise inducing components of the landing gear and to permitdeflection, articulation movement and stowage of the landing gear withthe attachment installed.
 2. Apparatus as in claim 1 in which a saidattachment comprises a deflector screen (15,17,76,93,94,111) adapted notto completely surround noise inducing components on the landing gear. 3.Apparatus as in claim 1 or 2 in which the attachment comprises an axleattachment (15) positionable in front of an axle (3) for nose gear ofthe aircraft.
 4. Apparatus as in claim 3 in which the axle attachment isshaped to enclose a towbar fitting (24).
 5. Apparatus as in claim 3 or 4in which the axle attachment includes generally cylindrical wheelextensions (30,31) extending between a central portion (32) thereof andeach wheel (33).
 6. Apparatus as in claim 1 or 2 in which the attachmentcomprises a steering mechanism attachment (17) for positioning in frontof a steering mechanism for the landing gear.
 7. Apparatus as in claim 1or 2 including an apertured strut attachment (16) positionable over asaid aperture (40) in the strut (14) to deflect air away from edges(41,42) of the aperture.
 8. Apparatus as in claim 7 in which theattachment (16) is shaped to blend in airflow leaving the attachmentwith airflow passing over streamwise extending surfaces (45,46) of thestrut, when in use.
 9. Apparatus as in claim 7 or 8 in which theattachment (16) is shaped to deflect air away from noise-inducingelements on the landing gear positioned to the rear of the said strut(14).
 10. Apparatus as in any preceding claim in which the attachment(15,17,76,93,94,111) is shaped to avoid regions of air stagnationthereover, when in use.
 11. Apparatus as in any preceding claimincluding an undertray attachment (76) shaped to extend in front of andunderneath a bogie beam (71) of the landing gear.
 12. Apparatus as inclaim 11 in which the undertray (76) includes a forward upwardlyextending aerodynamic surface (82) blended smoothly into an undersurface(83) extending underneath and along the bogie beam with a furtherlaterally facing surface extending longitudinally of the bogie beam oneither side of the undertray (89,90) depending from lateral edges(87,88) of the undertray.
 13. Apparatus as in claim 11 or 12 in whichthe undertray (76) is attachable to axles (72,73) on the landing gearbogie by means of band-type clamps (79,80) adapted to pass around theaxle/bogie beam and through at least one part-annular chamber (99,100)formed in an extension piece fixed to the undertray.
 14. Apparatus as inany preceding claim including a pair of articulating fairing attachments(93,94) for attachment to a forward articulation link (67,68) of a bogieof the landing gear, one articulated fairing being mounted to eacharticulation link with an aerodynamically contoured interface (105)being defined between the fairings comprising a generally sphericalelement (106) on one fairing (94) co-operating with generally circularsection (107) tubing of the other fairing (93).
 15. Apparatus as inclaim 14 when dependent upon any one of claims 11 to 13 in which theundertray (76) and lower articulation link fairing (93) in use lieclosely adjacent one another with the landing gear bogie (71) in itsapproach-to-landing configuration.
 16. Apparatus as in any precedingclaim including a door attachment (111) attachable to a door (112) whichis attached to the landing gear, the door extending generally streamwiseto one side of the landing gear, the door attachment (111) beingpositionable to extend from the door in front of at least a main leg(64) of the landing gear.
 17. Apparatus as in claim 16 in which the doorattachment (111) is adapted for sealing engagement with the door (112).18. Aircraft landing gear including apparatus according to any precedingclaim.
 19. Aircraft landing gear as in claim 18 in which at least onesaid attachment is shaped and positioned such that airflow over theattachment (16) during flight leaves the attachment substantially in thefree steam direction.
 20. Aircraft landing gear as in claim 18 or 19 inwhich at least one said attachment (111) is positioned to deflectincident air away from an air accelerating region formed between twocomponents (64,65) of the landing gear.
 21. Aircraft including landinggear according to any of claims 18 to 20.